Radio frequency switch circuit and apparatus having built-in coupler

ABSTRACT

A radio frequency switch circuit is described including a radio frequency switch and a coupler. The radio frequency switch includes a first band switch circuit connected between a first signal port and a common port, and configured to switch a first band signal. The coupler includes a first coupling wiring, disposed adjacent to a signal wiring formed between the common port of the radio frequency switch and an antenna port, and configured to form a first coupling signal with the signal wiring. A resonant frequency of the first coupling wiring is based on an inductance of the first coupling wiring and a capacitance of the radio frequency switch.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation Application based on U.S. applicationSer. No. 15/390,849, filed on Dec. 27, 2016, which claims the benefitunder USC 119(a) of Korean Patent Application Nos. 10-2016-0086254 and10-2016-0154330, filed on Jul. 7, 2016 and Nov. 18, 2016, respectively,in the Korean Intellectual Property Office, the entire disclosures ofwhich are incorporated herein by reference for all purposes.

BACKGROUND 1. Field

The following description relates to a radio frequency switch circuitand apparatus having a built-in coupler for use in a time divisionmultiplexing (TDM) communications system.

2. Description of Related Art

In general, in various communications systems using a time divisionmultiplexing (TDM) scheme, an antenna radio frequency (RF) switch isused between a transmitter and a receiver. In addition, in acommunications system performing multiple communications, a bandselection radio frequency (RF) switch is used between an antenna and aduplexer in order to switch between band signals.

The antenna RF switch described above alternately switches thetransmitter and the receiver on and off, thus, decreasing the entirepower consumption of a system and decreasing interference between thetransmitter and the receiver. In addition, the band selection RF switchselectively switches multiple bands on and off, thus, decreasing theentire power consumption of a system and decreasing interference betweenthe bands.

The RF switch described above may be used in communications systems suchas Bluetooth, cellular personal communications service (PCS), codedivision multiple access (CDMA), wideband CDMA (WCDMA), time divisionmultiple access (TDMA), global system for mobile communications (GSM),and wireless local area network (WLAN).

The RF switch requires performance characteristics such as low insertionloss, high power handling capability, high isolation, and the like.

In addition, an existing communications system includes a coupler tomonitor an output signal of a power amplifier (PA).

The coupler, however, has some operational disadvantages such asmismatching between antenna impedances and signal loss. The coupler maybe used, however, to control an output signal and control an inputsignal to improve efficiency of an entire system, and thus allow for anincrease in a battery discharge time and system adjustment.

However, existing communications systems may include a couplerimplemented or positioned separately from the RF switch, the RF switchmay be implemented as an integrated circuit (IC), and the coupler may beformed as a printed circuit board (PCB) pattern on a PCB or may bemounted as an individual component on a board or the PCB.

A coupler has a coupling factor, which can represent how much power isprovided to a coupled port of the coupler relative to the power of an RFsignal at the power input port. Such coupler typically causes aninsertion loss in an RF signal path. Thus, an RF signal received at apower input port of the coupler can have a lower power when provided atthe power output port of the coupler. Insertion loss can be due to aportion of the RF signal being provided to the coupled port (or to theisolated port) and/or to losses associated with the main transmissionline of the coupler. Thus, as described above, in a configuration inwhich a PCB-based coupler is implemented external to the RF switch,separately from an IC type RF switch, an area occupied by the PCB-basedcoupler is large, and efficiency is decreased due to the large loss ofthe coupler.

In addition, in a case in which the communications system includes abi-directional coupler to transmit/receive (Tx/Rx) coupling separatelyfrom the RF switch, the bi-directional coupler may detect bi-directionalsignals (forward and reverse signals). However, the bi-directionalcoupler occupies a large area in a communications module depending on afrequency being used. Also, efficiency of the power amplifier (PA) isfurther decreased due to line loss caused by implementation of the PCB.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In one general aspect, there is provided a radio frequency switchapparatus having a built-in coupler that has a decreased occupied areaand a size, and has an improved coupling characteristics usingcapacitances of switch devices in a switch-off state among switchdevices included in a radio frequency switch circuit. The radiofrequency switch apparatus includes an integrated circuit (IC) includinga radio frequency switch and the coupler.

In accordance with an embodiment, there is provided a radio frequencyswitch circuit, including: a radio frequency switch may include a firstband switch circuit connected between a first signal port and a commonport, and configured to switch a first band signal; and a coupler mayinclude a first coupling wiring, disposed adjacent to a signal wiringformed between the common port of the radio frequency switch and anantenna port, and configured to form a first coupling signal with thesignal wiring, wherein a resonant frequency of the first coupling wiringmay be based on an inductance of the first coupling wiring and acapacitance of the radio frequency switch.

The first band switch circuit may include a first series switch circuitconnected between the first signal port and the common port, and a firstshunt switch circuit connected between the first signal port and aground, and the resonant frequency of the first coupling wiring may bebased on the inductance of the first coupling wiring and a capacitanceof the first shunt switch circuit in a switch-off state.

The coupler further may include a second coupling wiring spaced apartfrom the first coupling wiring and adjacent to the signal wiring and theantenna port to form a second coupling signal with the signal wiring,and a resonant frequency of the second coupling wiring may be based onan inductance of the second coupling wiring and a capacitance of thefirst band switch circuit.

The first band switch circuit may include a first series switch circuitconnected between the first signal port and the common port, and a firstshunt switch circuit connected between the first signal port and aground, and the resonant frequency of the second coupling wiring may bebased on the inductance of the second coupling wiring and a capacitanceof the first shunt switch circuit in a switch-off state.

The resonant frequency of the first coupling wiring may coincide with afrequency of the first band signal transmitted from the first bandswitch circuit based on the inductance of the first coupling wiring anda capacitance of the first shunt switch circuit in a switch-off state.

The resonant frequency of the first coupling wiring may be based on acapacitance of the first shunt switch circuit in a switch-off state, anda mutual capacitance and a mutual inductance between the signal wiringand the first coupling wiring.

A resonant frequency of the coupler may be based on

${{Fres} = {\frac{1}{2\;\pi*{Coff}}\left( {\sqrt{\frac{Cm}{Lm}} - \frac{1}{Zo}} \right)}},$where Coff may be a capacitance of the first shunt switch circuit in aswitch-off state, Cm may be a mutual capacitance between the signalwiring and the first coupling wiring, Lm may be a mutual inductancebetween the signal wiring and the first coupling wiring, and Zo may bean intrinsic impedance of the first signal port.

The radio frequency switch and the coupler may be integrally formed onan integrated circuit board.

In accordance with an embodiment, there is provided a radio frequencyswitch apparatus, including: a radio frequency switch may include afirst band switch circuit connected between a first signal port and acommon port, and configured to switch a first band signal; a coupler mayinclude a first coupling wiring disposed adjacent to a signal wiringformed between the interstage matching circuit and an antenna port toform a first coupling signal with the signal wiring; and an interstagematching circuit connected to the common port and configured to performimpedance matching between the radio frequency switch and the coupler,wherein a resonant frequency of the first coupling wiring may be basedon an inductance of the first coupling wiring and a capacitance of theradio frequency switch.

The first band switch circuit may include a first series switch circuitconnected between the first signal port and the common port and a firstshunt switch circuit connected between the first signal port and aground, and the resonant frequency of the first coupling wiring may bebased on the inductance of the first coupling wiring and a capacitanceof the first shunt switch circuit in a switch-off state.

The coupler further may include a second coupling wiring spaced apartfrom the first coupling wiring, and adjacent to the signal wiring andthe antenna port to form a second coupling signal with the signalwiring, and a resonant frequency of the second coupling wiring may bebased on an inductance of the second coupling wiring and a capacitanceof the first band switch circuit.

The first band switch circuit may include a first series switch circuitconnected between the first signal port and the common port and a firstshunt switch circuit connected between the first signal port and aground, and the resonant frequency of the second coupling wiring may bebased on the inductance of the second coupling wiring and a capacitanceof the first shunt switch circuit in a switch-off state.

The resonant frequency of the first coupling wiring coincides with afrequency of the first band signal transmitted from the first bandswitch circuit based on the inductance of the first coupling wiring anda capacitance of the first shunt switch circuit in a switch-off state.

The resonant frequency of the first coupling wiring may be based on acapacitance of the first shunt switch circuit in a switch-off state, anda mutual capacitance and a mutual inductance between the signal wiringand the first coupling wiring.

A resonant frequency of the coupler may be based on

${{Fres} = {\frac{1}{2\;\pi*{Coff}}\left( {\sqrt{\frac{Cm}{Lm}} - \frac{1}{Zo}} \right)}},$where Coff may be a capacitance of the first shunt switch circuit in theswitch-off state, Cm may be the mutual capacitance between the signalwiring and the first coupling wiring, Lm may be the mutual inductancebetween the signal wiring and the first coupling wiring, and Zo may bean intrinsic impedance of the first signal port.

The radio frequency switch and the coupler may be integrally formed onan integrated circuit board.

In accordance with an embodiment, there is provided an apparatus,including: a first band switch circuit may include a first series switchcircuit and a first shunt switch circuit, wherein the first seriesswitch circuit may be connected between a signal port and a common port;and a coupler may include a signal wiring may include one end connectedto the common port and another end connected to an antenna port, and afirst coupling wiring disposed coextensive to the signal wiring to forma coupling with the signal wiring and configured to produce a firstcoupling signal, wherein a resonant frequency of the first couplingwiring may be based on an inductance of the first coupling wiring and acapacitance of the first shunt switch circuit in a switch-off state.

The first coupling wiring may be disposed between a first detection portand a resistor.

In response to the first shunt switch circuit being in the switch-offstate and the first series switch circuit being in a switch-on state,the first band switch circuit transmits a first band signal to thecoupler.

The apparatus may further include a second coupling wiring disposedcoextensive to the signal wiring, diametrically opposite to the firstcoupling wiring, and configured to form a coupling with the signalwiring and produce a second coupling signal to monitor signal receptionstrength.

The apparatus may further include an output matching circuit disposedbetween the coupler and an antenna terminal configured to match animpedance of the first band switch circuit and match an impedance of theantenna terminal and an impedance of the coupler to each other todecrease transfer loss of signals.

The impedance of the coupler may be different from the impedance of thefirst band switch circuit.

The apparatus may further include a radio frequency switch may includethe first band switch circuit and connected between the signal port andthe common port; and an interstage matching circuit disposed between theradio frequency switch and the coupler configured to match impedancesbetween the radio frequency switch and the coupler.

The signal wiring may be disposed on a first layer of an integratedcircuit, the first and second coupling wirings may be disposed on asecond layer of the integrated circuit, and corresponding resistors ofthe first and second coupling wirings, corresponding grounds of thefirst and second coupling wirings, and a ground part of the integratedcircuit may be disposed on a third layer of the integrated circuit.

The second layer may be disposed below the first layer, and the thirdlayer may be disposed below the second layer.

The first and second coupling wirings may be disposed on a layer of anintegrated circuit different from a layer on which a ground part of theintegrated circuit may be disposed to relatively increase a distancebetween the first and second coupling wirings and the ground part of theintegrated circuit.

In accordance with another embodiment, there is provided an apparatus,including: a first band switch circuit may include a first series switchcircuit and a first shunt switch circuit, wherein the first seriesswitch circuit may be connected between a signal port and a common port;and a coupler may include a signal wiring may include one end connectedto the common port and another end connected to an antenna port, and afirst coupling wiring disposed coextensive to the signal wiring to forma coupling with the signal wiring and configured to produce a firstcoupling signal, wherein a resonant frequency of the first couplingwiring may be determined based on a capacitance of the first shuntswitch circuit in a switch-off state, and a mutual capacitance and amutual inductance between the signal wiring and the first couplingwiring.

The first coupling wiring and the signal wiring may be coupled to eachother to form the mutual capacitance and the mutual inductance betweenthe first coupling wiring and the signal wiring.

The first shunt switch circuit may be connected between the signal portand a ground, and the first shunt switch circuit changes from aswitch-on state to the switch-off state based on a second gate signal ofthe first shunt switch circuit.

In response to the first shunt switch circuit being in the switch-offstate and the first series switch circuit being in a switch-on state,the first band switch circuit transmits a first band signal to thecoupler.

The resonant frequency, Fres, may be based on a following relationship

${{Fres} = {\frac{1}{2\;\pi*{Coff}}\left( {\sqrt{\frac{Cm}{Lm}} - \frac{1}{Zo}} \right)}},$where, Coff may be the capacitance of the first shunt switch circuit inthe switch-off state, Cm may be the mutual capacitance between thesignal wiring and the first coupling wiring, Lm may be the mutualinductance between the signal wiring and the first coupling wiring, andZo may be an intrinsic impedance of the signal port.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating a radio frequency switch circuithaving a built-in coupler, according to an embodiment;

FIG. 2 is a schematic view illustrating a radio frequency switchapparatus having the built-in coupler, according to an embodiment;

FIG. 3 is another schematic view illustrating a radio frequency switchapparatus having a built-in coupler, according to an embodiment;

FIG. 4 is another schematic view illustrating a radio frequency switchapparatus having the built-in coupler, according to an embodiment;

FIG. 5 is a schematic view illustrating a first band switch circuit,according to an embodiment;

FIG. 6 is an equivalent circuit diagram of a switch-on state of thefirst band switch circuit of FIG. 5;

FIG. 7 is a schematic view illustrating an N-th band switch circuit,according to an embodiment;

FIG. 8 is an equivalent circuit diagram of a switch-on state of the N-thband switch circuit of FIG. 7;

FIGS. 9A through 9C are schematic views illustrating the coupler of FIG.2;

FIG. 10 is a view for describing the coupler of FIG. 1; and

FIGS. 11A and 11B are graphs illustrating performance of a couplerformed on a printed circuit board, and performance of an integratedcircuit (IC) built-in coupler, according to an embodiment, respectively.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent after an understanding of thedisclosure of this application. For example, the sequences of operationsdescribed herein are merely examples, and are not limited to those setforth herein, but may be changed as will be apparent after anunderstanding of the disclosure of this application, with the exceptionof operations necessarily occurring in a certain order. Also,descriptions of features that are known in the art may be omitted forincreased clarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided merelyto illustrate some of the many possible ways of implementing themethods, apparatuses, and/or systems described herein that will beapparent after an understanding of the disclosure of this application.

Throughout the specification, when an element, such as a layer, region,or substrate, is described as being “on,” “connected to,” or “coupledto” another element, it may be directly “on,” “connected to,” or“coupled to” the other element, or there may be one or more otherelements intervening therebetween. In contrast, when an element isdescribed as being “directly on,” “directly connected to,” or “directlycoupled to” another element, there can be no other elements interveningtherebetween.

As used herein, the term “and/or” includes any one and any combinationof any two or more of the associated listed items.

Although terms such as “first,” “second,” and “third” may be used hereinto describe various members, components, regions, layers, or sections,these members, components, regions, layers, or sections are not to belimited by these terms. Rather, these terms are only used to distinguishone member, component, region, layer, or section from another member,component, region, layer, or section. Thus, a first member, component,region, layer, or section referred to in examples described herein mayalso be referred to as a second member, element, feature, component,region, layer, or section without departing from the teachings of theexamples.

Spatially relative terms such as “above,” “upper,” “below,” and “lower”may be used herein for ease of description to describe one element'srelationship to another element as shown in the figures. Such spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device in the figures is turned over,an element described as being “above” or “upper” relative to anotherelement will then be “below” or “lower” relative to the other element.Thus, the term “above” encompasses both the above and below orientationsdepending on the spatial orientation of the device. The device may alsobe oriented in other ways (for example, rotated 90 degrees or at otherorientations), and the spatially relative terms used herein are to beinterpreted accordingly.

The terminology used herein is for describing various examples only, andis not to be used to limit the disclosure. The articles “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. The terms “comprises,” “includes,”and “has” specify the presence of stated features, numbers, operations,members, elements, and/or combinations thereof, but do not preclude thepresence or addition of one or more other features, numbers, operations,members, elements, and/or combinations thereof.

Due to manufacturing techniques and/or tolerances, variations of theshapes shown in the drawings may occur. Thus, the examples describedherein are not limited to the specific shapes shown in the drawings, butinclude changes in shape that occur during manufacturing.

The features of the examples described herein may be combined in variousways as will be apparent after an understanding of the disclosure ofthis application. Further, although the examples described herein have avariety of configurations, other configurations are possible as will beapparent after an understanding of the disclosure of this application.

FIG. 1 is a schematic view illustrating a radio frequency switch circuithaving a built-in coupler, according to an embodiment.

Referring to FIG. 1, the radio frequency switch circuit 100 having abuilt-in coupler, according to an embodiment, includes a radio frequencyswitch 110 and a coupler 120.

The radio frequency switch 110 includes at least one first band switchcircuit SWB1, connected between at least one first signal port P1 and acommon port Pcom. The first band switch circuit SWB1 includes acapacitor Coff. The radio frequency switch 110 is configured to switch afirst band signal SB1 received at the first signal port P1.

In some embodiments, the radio frequency switch 110 includes one firstband switch circuit SWB1. Alternatively, the radio frequency switch 110may include first to N-th band switch circuits SWB1 to SWBN (here, Nindicates a natural number of 2 or more).

In this alternative embodiment, the first band switch circuit SWB1 maybe connected between the first signal port P1 and the common port Pcom,and may switch the first band signal SB1, while the N-th band switchcircuit SWBN may be connected between an N-th signal port PN and thecommon port Pcom, and may switch an N-th band signal SBN.

Because the radio frequency switch 110 is similarly applied to thevarious embodiments described, an overlapping description for the radiofrequency switch 110 will be omitted to avoid redundancy.

The coupler 120 includes a first coupling wiring LCPL1 between a firstdetection port PCPL1 and an end point of a resistor R11, which isgrounded GND1 at another end thereof. The first coupling wiring LCPL1 isdisposed adjacent to, coextensive to, parallel to, substantiallyproximate to, or near to a signal wiring Lant to form a first couplingsignal with the signal wiring Lant. The signal wiring Lant is positionedwithin the coupler 120, between one end P11 and another end P12, asshown in FIG. 1. The coupler 120 is formed, positioned, or disposedbetween the common port Pcom of the radio frequency switch 110 and anantenna port Pant to form a coupling with the signal wiring Lant andoutput a first coupling signal from the first detection port PCPL1.

In this case, a resonant frequency Fres from the first coupling wiringLCPL1 is determined by an inductance of the first coupling wiring LCPL1and a capacitance Coff of the radio frequency switch 110.

In an example, the one end P11 of the signal wiring Lant is connected tothe common port Pcom of the radio frequency switch 110, and the otherend P12 of the signal wiring Lant is connected to the antenna port Pant.

FIG. 2 is a schematic view illustrating a radio frequency switchapparatus having the built-in coupler, according to an embodiment.

Referring to FIG. 2, the radio frequency switch apparatus having abuilt-in coupler includes a radio frequency switch circuit 100 and anoutput matching circuit 250.

The coupler 120 of the radio frequency switch circuit 100 includes asecond coupling wiring LCPL2, in addition to a structure illustrated inFIG. 1.

The second coupling wiring LCPL2 is disposed between a first detectionport PCPL2 and an end point of a resistor R21, which is grounded GND2 atanother end thereof. The second coupling wiring LCPL2 is disposedadjacent to, coextensive to, parallel to, substantially proximate to, ornear to the signal wiring Lant described with reference to FIG. 1 toform a second coupling signal with the signal wiring Lant.

In an example, a resonant frequency Fres from the second coupling wiringLCPL2 is determined by an inductance of the second coupling wiring LCPL2and the capacitance Coff of the first band switch circuit SWB1.

The output matching circuit 250 is connected between the antenna portPant of the radio frequency switch circuit 100 and an antenna terminalTout to which an antenna is connected, and may match impedances betweenthe antenna port Pant and the antenna terminal Tout to decrease transferloss of signals.

Referring to FIGS. 1 and 2, the radio frequency switch circuit 100having a built-in coupler includes the radio frequency switch 110 andthe coupler 120 and is formed on one or a single integrated circuitboard using a same manufacturing process as to be implemented whenforming a single integrated circuit.

As an example, the integrated circuit is an integrated circuit using asemiconductor board such as a silicon-on-insulator (SOI), or the like,and, for example, in an embodiment in which a semiconductor board isused such as the SOI, or the like, loss may be decreased due to highresistive board characteristics. The radio frequency switch 110 and thecoupler 120 may be disposed as adjacent to, coextensive to, parallel to,substantially proximate to, or near to each other as possible tosignificantly decrease insertion loss.

Therefore, when the radio frequency switch circuit 100 having a built-incoupler, according to the embodiment, is used, the insertion loss isreduced, and an area occupied by the coupler and a size of the coupleris decreased.

As previously explained, the first coupling wiring LCPL1 of the coupler120 are connected to the first detection port PCPL1 and the firstresistor R11.

The first detection port PCPL1 is connected to one end of the firstcoupling wiring LCPL1 disposed adjacent to, coextensive to, parallel to,substantially proximate to, or near to the common port Pcom, and outputa first coupling signal coupled from the signal wiring Lant. In anexample, the first coupling signal provided through the first couplingwiring LCPL1 may be used as a signal for monitoring transmission power.

The first resistor R11 is connected between the other end of the firstcoupling wiring LCPL1 disposed adjacent to, coextensive to, parallel to,substantially proximate to, or near to the antenna port Pant and theground GND1, and matches impedances to each other. In an example, thefirst resistor R11, which is a resistor for matching impedances to eachother, is set to 50Ω.

In addition, the second coupling wiring LCPL2 of the coupler 120 isconnected between the second detection port PCPL2 and the secondresistor R21.

The second detection port PCPL2 is connected to one end of the secondcoupling wiring LCPL2 disposed adjacent to, coextensive to, parallel to,substantially proximate to, or near to the antenna port Pant, andoutputs a second coupling signal coupled from the signal wiring Lant. Inan example, the second coupling signal provided through the secondcoupling wiring LCPL2 is used as a signal to monitor reception strength.The second coupling wiring LCPL2 is diametrically opposite to the firstcoupling wiring LCPL1 or on another side of the signal wiring Lant onwhich the first coupling wiring LCPL1 is disposed.

The second resistor R21 is connected between the other end of the secondcoupling wiring LCPL2 disposed adjacent to, coextensive to, parallel to,substantially proximate to, or near to the common port Pcom and aground, and match impedances to each other. In an example, the secondresistor R21, which is a resistor for matching impedances to each other,may be set to 50Ω as an example.

As described above, an area occupied by the coupler and a size of thecoupler is decreased and loss of the coupler itself is improved. In anexample in which the coupler 120 is implemented together with the radiofrequency switch 110 by the integrated circuit IC, as compared to anexample in which the coupler 120 is formed as a printed circuit board(PCB) pattern on a board, or is mounted as an individual coupler deviceas a board.

As illustrated in FIGS. 1 and 2, in an integrated circuit including theradio frequency switch 110 and the coupler 120, an impedance of thecoupler 120 connected to the antenna terminal, of which an impedance is50Ω, and an impedance of the radio frequency switch 110 may not coincidewith each other. As an example, the impedance of the radio frequencyswitch 110 is not 50Ω, and because the coupler 120 is connected to theantenna terminal, the impedance of the coupler 120 is 50Ω, which is thesame as that of the antenna terminal.

In this example, an output matching circuit 250 is disposed between thecoupler 120 and the antenna terminal Tout in order to match theimpedance of the radio frequency switch 110 and the impedance of theantenna terminal and the coupler 120 to each other. Although the outputmatching circuit 250 is illustrated in FIG. 2 as being external to theradio frequency switch apparatus 100, in an alternative embodiment, theoutput matching circuit 250 may be integrated within the radio frequencyswitch apparatus 100.

Therefore, the output matching circuit 250 matches the impedance betweenthe radio frequency switch circuit 100 and the antenna terminal Tout. Asa result, the impedance is matched between the radio frequency switch110 and the coupler 120, and the impedance is matched between thecoupler 120 and the antenna terminal.

FIG. 3 is another schematic view illustrating a radio frequency switchapparatus having a built-in coupler, according to an embodiment.

Referring to FIG. 3, the radio frequency switch apparatus having abuilt-in coupler, according to an embodiment, includes a radio frequencyswitch circuit 100 and an interstage matching circuit 220. Although theinterstage matching circuit 220 is illustrated in FIG. 3 as beingexternal to the radio frequency switch apparatus 100, in an alternativeembodiment, the interstage matching circuit 220 may be integrated withinthe radio frequency switch apparatus 100.

The radio frequency switch circuit 100 is the same as the radiofrequency switch circuit described with reference to FIGS. 1 and 2, andthus, a detailed description therefor will be omitted.

The coupler 120 includes a first coupling wiring LCPL1. The firstcoupling wiring LCPL1 is disposed adjacent to, coextensive to, parallelto, substantially proximate to, or near to a signal wiring Lant formedbetween the interstage matching circuit 220 and an antenna port Pant toform a first coupling signal with a portion of the signal wiring Lant.In an example, one end P21 of the signal wiring Lant is connected to theinterstage matching circuit 220, and the other end P22 of the signalwiring Lant is connected to the antenna port Pant.

The interstage matching circuit 220 is connected between the common portPcom of the radio frequency switch 110 and the coupler 120. Theinterstage matching circuit 220 is configured to match impedancesbetween the radio frequency switch 110 and the coupler 120.

In addition, a resonant frequency Fres from the first coupling wiringLCPL1 is determined by an inductance of the first coupling wiring LCPL1and a capacitance Coff of the radio frequency switch 110.

FIG. 4 is another schematic view illustrating a radio frequency switchapparatus having the built-in coupler, according to an embodiment.

Referring to FIG. 4, the radio frequency switch apparatus having abuilt-in coupler according to the exemplary embodiment includes a radiofrequency switch circuit 100 and an interstage matching circuit 220.

The coupler 120 of the radio frequency switch circuit 100 also includesa second coupling wiring LCPL2, in addition to a structure illustratedin FIG. 3.

The second coupling wiring LCPL2 may be disposed adjacent to the signalwiring Lant, described with reference to FIG. 3, to form second couplingsignal with the signal wiring Lant.

In an example, a resonant frequency Fres by the second coupling wiringLCPL2 is determined by an inductance of the second coupling wiring LCPL2and a capacitance Coff of the first band switch circuit SWB1.

The interstage matching circuit 220 is connected between the common portPcom of the radio frequency switch 110 and the coupler 120. Theinterstage matching circuit 220 is configured to match impedancesbetween the radio frequency switch 110 and the coupler 120.

Furthermore, as illustrated in FIGS. 3 and 4, in an integrated circuitincluding the radio frequency switch 110 and the coupler 120, animpedance of the coupler 120 connected to the antenna terminal, of whichan impedance is 50Ω, does not coincide with or is different from theimpedance of the radio frequency switch 110. As an example, theimpedance of the radio frequency switch 110 is not 50Ω, and because thecoupler 120 is connected to an antenna, the impedance of the coupler 120is 50Ω, which is the same as the impedance of the antenna terminal.

In an example, the interstage matching circuit 220 is disposed betweenthe radio frequency switch 110 and the coupler 120 in order to matchimpedances between the radio frequency switch 110 and the coupler 120.In an example, the interstage matching circuit 220 is disposed outsidethe integrated circuit including the radio frequency switch 110 and thecoupler 120.

The interstage matching circuit 220 is connected between the radiofrequency switch 110 and the coupler 120. The interstage matchingcircuit 220 is configured to match impedances between the radiofrequency switch 110 and the coupler 120.

FIG. 5 is a schematic view illustrating a first band switch circuit,according to an embodiment; FIG. 6 is an equivalent circuit diagram of aswitch-on state of the first band switch circuit of FIG. 5; FIG. 7 is aschematic view illustrating an N-th band switch circuit, according to anembodiment; and FIG. 8 is an equivalent circuit diagram of a switch-onstate of the N-th band switch circuit of FIG. 7.

Referring to FIGS. 5 and 6, the first band switch circuit SWB1 includesa first series switch circuit SW1-1 and a first shunt switch circuitSW1-2.

The first series switch circuit SW1-1 is connected between the firstsignal port P1 and a common port Pcom, and changes from a switch-onstate to a switch-off state, and vice-versa, depending on a first gatesignal SG1-1. As an example, the first series switch circuit SW1-1includes one or more switch devices M1-1, such as a metal oxidesemiconductor field effect transistor (MOSFET), N-channel MOSFET, orP-channel MOSFET, connected in series between the first signal port P1and the common port Pcom.

The first shunt switch circuit SW1-2 is connected between the firstsignal port P1 and a ground, and changes from a switch-on state to aswitch-off state, and vice-versa, depending on a second gate signalSG1-2. As an example, the first shunt switch circuit SW1-2 includes oneor more switch devices M1-2, such as a MOSFET, N-channel MOSFET, orP-channel MOSFET, connected in series between the first signal port P1and the ground.

Further, the switch devices M1-1 and M1-2 may be metal oxidesemiconductor (MOS) transistors, and types of MOS transistors are notparticularly limited.

In this example, in order for the first band switch circuit SWB1 totransfer the first band signal SB1, the first shunt switch circuit SW1-2changes to a switch-off state, based on a low voltage level of thesecond gate signal SG1-2 in response to the first series switch circuitSW1-1 being in a switch-on state, based on a high voltage level of thefirst gate signal SG1-1. In this case, the first shunt switch circuitSW1-2 in the switch-off state has a capacitance Coff.

Further, a resonant frequency Fres by the first coupling wiring LCPL1 isdetermined by an inductance of the first coupling wiring LCPL1 and acapacitance Coff of the first shunt switch circuit SW1-2 in theswitch-off state.

In contrast, in order for the first band switch circuit SWB1 to blockthe first band signal SB1, the first shunt switch circuit SW1-2 changesto a switch-on state, depending on a high voltage level of the secondgate signal SG1-2 in response to the first series switch circuit SW1-1being in a switch-off state, and depending on a low voltage level of thefirst gate signal SG1-1.

Referring to FIGS. 7 and 8, the N-th band switch circuit SWBN includesan N-th series switch circuit SWN-1 and an N-th shunt switch circuitSWN-2.

The N-th series switch circuit SWN-1 is connected between the N-thsignal port PN and a common port Pcom, and changes from a switch-onstate to a switch-off state, and vice-versa, depending on a first gatesignal SGN-1. As an example, the N-th series switch circuit SWN-1includes one or more switch devices MN-1, such as a MOSFET, N-channelMOSFET, or P-channel MOSFET, connected in series between the N-th signalport PN and the common port Pcom.

The N-th shunt switch circuit SWN-2 is connected between the N-th signalport PN and a ground, and changes from a switch-on state to a switch-offstate, and vice-versa, depending on a second gate signal SGN-2. As anexample, the N-th shunt switch circuit SWN-2 includes one or more switchdevices MN-2, such as a MOSFET, N-channel MOSFET, or P-channel MOSFET,connected in series between the N-th signal port PN and the ground.

In an embodiment, the one or more switch devices MN-1 and MN-2 may beMOS transistors, and types of MOS transistors are not particularlylimited.

In an embodiment, in order for the N-th band switch circuit SWBN totransfer the N-th band signal SBN, the N-th shunt switch circuit SWN-2changes to a switch-off state based on a low voltage level of the secondgate signal SGN-2 in response to the N-th series switch circuit SWN-1being in a switch-on state based on a high voltage level of the firstgate signal SGN-1. In this embodiment, the N-th shunt switch circuitSWN-2 in the switch-off state has a capacitance Coff.

In this embodiment, a resonant frequency Fres by the first couplingwiring LCPL1 is based on or is determined by an inductance of the firstcoupling wiring LCPL1 and a capacitance Coff of the N-th shunt switchcircuit SWN-2 in the switch-off state.

Further, in contrast, in order for the N-th band switch circuit SWBN toblock the N-th band signal SBN, the N-th shunt switch circuit SWN-2changes to a switch-on state, based on a high voltage level of thesecond gate signal SGN-2 in response to the N-th series switch circuitSWN-1 being in a switch-off state, based on a low voltage level of thefirst gate signal SGN-1.

Referring to FIGS. 5 through 8, the number of semiconductor switchdevices included in each of the first to N-th shunt switch circuitsSW1-2 to SWN-2 may be determined by considering an entire capacitanceCoff of switch devices in a switch-off state in the corresponding shuntswitch circuits determining the resonant frequency Fres of the coupler120, because capacitances of the respective semiconductor switch devicesin the switch-off state are summed up to have an influence on theresonant frequency Fres of the coupler 120.

Referring to FIGS. 5 through 8, the resonant frequency Fres by the firstcoupling wiring LCPL1 may coincide with a frequency of the first bandsignal SB1 transferred through the first band switch circuit SWB1 by theinductance of the first coupling wiring LCPL1 and the capacitance Coffof the first shunt switch circuit SW1-2 in the switch-off state.

In a respective embodiments, the coupler 120 may be formed on asingle-layer semiconductor board or may be formed on a multilayersemiconductor board in order to be manufactured in a smaller size, anexample of which will be described with reference to FIGS. 9A through9C.

FIGS. 9A through 9C are schematic views illustrating the coupler of FIG.2. FIG. 9A is a perspective view of the coupler 120. FIG. 9B is a viewillustrating the first and second coupling wirings LCPL1 and LCPL2 ofFIG. 9A. FIG. 9C is an enlarged view of the first coupling wiring LCPL1,the first resistor R11 (see FIG. 2), and a first ground GND1.

Referring to FIGS. 9A and 9B, the signal wiring Lant is disposed on afirst layer, the first and second coupling wirings LCPL1 and LCPL2 aredisposed on a second layer, and the first and second resistors, firstand second grounds GND1 and GND2, and a ground part GND of theinsulating layer are disposed on a third layer.

The second layer is disposed below the first layer, and the third layermay be disposed below the second layer. Wirings between the first andsecond layers and signal wirings (or ground wirings) of the second andthird layers are electrically connected to each other through conductivevias. In an example, the first and second resistors disposed on thethird layer are electrically connected to corresponding coupling wiringsand a ground by a conductor pattern CP.

In this embodiment, the first and second coupling wirings LCPL1 andLCPL2 are disposed on a layer different from a layer on which the groundpart GND is disposed, such that a distance between the first and secondcoupling wirings LCPL1 and LCPL2 and the ground part GND in theintegrated circuit is relatively increased. Therefore, isolation betweenthe first and second coupling wirings LCPL1 and LCPL2 and the groundpart GND is improved.

In FIGS. 9A through 9C, a coupler structure including the signal wiringLant and the first and second coupling wirings LCPL1 and LCPL2 is onlyan example, and the various embodiments are not limited thereto.

Furthermore, the resonant frequency Fres of the first coupling wiringLCPL1 is determined based on the capacitance Coff of the first shuntswitch circuit SW1-2 in the switch-off state, and a mutual capacitanceCm and a mutual inductance Lm between the signal wiring Lant and thefirst coupling wiring LCPL1. In an example, the inductance of the firstcoupling wiring LCPL1 is the mutual inductance. This will be describedwith reference to FIG. 10.

FIG. 10 is a view to describe the coupler of FIG. 1.

FIG. 10 is an equivalent circuit diagram of the coupler in the radiofrequency switch circuit 100 in which the first band switch circuit SWB1is in a switch-on state. The first band switch circuit SWB1 is the firstband switch circuit of N-th band switch circuits of the radio frequencyswitch 110.

Referring to FIGS. 1 and 10, the coupler 120 includes the first couplingwiring LCPL1, which is represented as an inductor. In this case, thesignal wiring Lant, between the common port Pcom of the radio frequencyswitch 110 and the antenna port Pant, is an inductor.

In this embodiment, the first coupling wiring LCPL1 and the signalwiring Lant are disposed adjacent to each other and coupled to eachother, such that a mutual capacitance Cm and a mutual inductance Lm isformed between the first coupling wiring LCPL1 and the signal wiringLant.

The resonant frequency Fres of the coupler 120 is determined asrepresented by the following Equation 1:

$\begin{matrix}{{Fres} = {\frac{1}{2\;\pi*{Coff}}{\left( {\sqrt{\frac{Cm}{Lm}} - \frac{1}{Zo}} \right).}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

Here, Coff is a capacitance of the first shunt switch circuit SW1-2 inthe switch-off state, Cm is the mutual capacitance between the signalwiring Lant and the first coupling wiring LCPL1, Lm is the mutualinductance between the signal wiring Lant and the first coupling wiringLCPL1, and Zo is an intrinsic impedance (a line intrinsic impedance) ofthe first signal port P1.

Referring to Equation 1, in the radio frequency switch apparatus havinga built-in coupler, a switch in a switch-off state in the radiofrequency switch circuit is represented by a capacitance Coff. Inaddition, in Equation 1, a coupling factor and an isolation value of thecoupler are set using the mutual capacitance Cm and the mutualinductance Lm, and the capacitance Coff has an influence on a resonantpoint of the coupling factor and the isolation of the coupler. Inconsideration of this, the mutual capacitance Cm and the mutualinductance Lm are determined.

As an example, in an example in which the resonant frequency of thecoupler is set to coincide with a use frequency, excellent couplingcharacteristics may be secured.

In addition, referring to FIG. 10, a level at which an original signalinterferes and is viewed in the coupler 120, when a signal input throughthe first signal port P1 is transmitted through an antenna connected tothe antenna port, is called a ‘coupling factor’. A level at which asignal is viewed in the coupler 120 when the signal is received in areverse direction (from the antenna port to the first signal port P1) iscalled ‘isolation.’ In this case, because the isolation is an undesiredsignal, the lower the isolation, the better.

In addition, a phase difference depending on a direction of the couplermay be present in coupling by the mutual inductance Lm, different thanin the case of coupling by the mutual capacitance Cm. The couplingfactor and the isolation as described above may be represented by thefollowing Equations 2 and 3:

$\begin{matrix}{{CouplingFactor} = {\frac{Vcpl}{Vinput} = {\frac{1}{2}\left( {{{jwZo}*{Cm}} + {{jw}\frac{Lm}{Zo}}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack \\{{isolation} = {\frac{Visolation}{Vinput} = {\frac{1}{2}{\left( {{{jwZo}*{Cm}} - {{jw}\frac{Lm}{Zo}}} \right).}}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

Here, Vcpl is a coupling voltage, Vinput is an input voltage inputthrough the first signal port P1, Voutput is an output voltage outputthrough the antenna port, and w is an angular frequency (=2πf (here, fis a frequency)).

It may be appreciated from Equations 2 and 3 that the coupling factorand the isolation may be determined based on the mutual capacitance Cmand the mutual inductance Lm.

FIG. 11A is a graph illustrating non-ideal performance of a couplerformed on a printed circuit board. FIG. 11B is a graph illustrating anideal performance of an integrated circuit (IC) built-in coupler inaccord with an embodiment.

In FIG. 11A, G11 is a graph illustrating insertion loss characteristics,G12 is a graph illustrating directivity characteristics, G13 is a graphillustrating the characteristics of a coupling factor, and G14 is agraph illustrating the characteristics of isolation.

In addition, in FIG. 11B, G21 is a graph illustrating insertion losscharacteristics, G22 is a graph illustrating directivitycharacteristics, G23 is a graph illustrating the characteristics of acoupling factor, and G24 is a graph illustrating the characteristics ofisolation.

As an example, when comparing performances of the couplers at 960 MHzwith each other, marked in FIGS. 11A and 11B, G11 is −0.24 [dB], G12 is−11.69 [dB], G13 is −20.22 [dB], and G14 is −31.92 [dB] in FIG. 11A, andG21 is −0.17 [dB], G22 is −19.06 [dB], G23 is −19.31 [dB], and G24 is−38.37 [dB] in FIG. 11B.

It may be appreciated from FIGS. 11A and 11B that performance of anideal IC-based coupler, according to an embodiment, is improved whencompared to performance of a non-ideal PCB-based coupler. For example,insertion loss was increased from −0.24 [dB] to −0.17 [dB] by 0.07 [dB].

In addition, a space of about 90% may be saved in the IC-based coupler,according to an embodiment, compared to the non-ideal PCB-based coupler.

The radio frequency switch circuit and apparatus having a built-incoupler, according to an embodiment as described above, may be used fora frequency division multiplexing (FDM) communications scheme, but mayalso be appropriate for a time division multiplexing (TDM)communications scheme.

The TDM communications scheme is a scheme to detect signals through asignal wiring, which is a common communications wiring, without usingsignal wirings for each band paths. This communications scheme has atleast an advantage in terms of corresponding size and cost, and specificband signals are transmitted and received at any one point in time inthe TDM communications scheme such that the signals are more accuratelydetected through the signal wiring, which is a common communicationswiring in the TDM communications scheme, in contrast with the FDMcommunications scheme.

As set forth above, according to an embodiment, a coupler is built in aradio frequency switch to implement an integrated circuit (IC), where anarea occupied by the coupler and the size of the coupler is decreased,and signal loss is decreased when compared to a coupler formed of aPCB-based pattern.

Because one coupler is disposed between the common port of the radiofrequency switch and the antenna port, the radio frequency switchcircuit having a built-in coupler according to an embodiment, caninclude one coupler compared to other circuits, in which couplers aredisposed in each of a number of band paths. Some of the many advantagesof the radio frequency switch circuit having a built-in coupler,according to the embodiment, is smaller in the area to be occupied bythe coupler and a manufacturing cost of the coupler is reduced, andsignals may be detected through the coupler immediately beforetransmitting the signals through the antenna, and thus, the signals aremore accurately detected.

In addition, capacitances of switch devices in a switch-off state, amongswitch devices included in the radio frequency switch, are used to allowa resonant frequency to coincide with a corresponding band frequency,such that loss of the coupler is decreased, thus, improving performancecharacteristics of the coupler.

Further, signal and power loss of the coupler is decreased, thus,relatively decreasing power consumption.

While various embodiments have been shown and described above, it willbe apparent after an understanding of the disclosure of this applicationthat modifications and variations could be made without departing fromthe scope of the present application, as defined by the appended claims.

While this disclosure includes specific examples, it will be apparentafter an understanding of the disclosure of this application thatvarious changes in form and details may be made in these exampleswithout departing from the spirit and scope of the claims and theirequivalents. The examples described herein are to be considered in adescriptive sense only, and not for purposes of limitation. Descriptionsof features or aspects in each example are to be considered as beingapplicable to similar features or aspects in other examples. Suitableresults may be achieved if the described techniques are performed in adifferent order, and/or if components in a described system,architecture, device, or circuit are combined in a different manner,and/or replaced or supplemented by other components or theirequivalents. Therefore, the scope of the disclosure is defined not bythe detailed description, but by the claims and their equivalents, andall variations within the scope of the claims and their equivalents areto be construed as being included in the disclosure.

What is claimed is:
 1. A radio frequency switch circuit, comprising: aradio frequency switch comprising switch devices connected between asignal port and a common port; and a coupler comprising a first couplingwiring, disposed adjacent to a signal wiring formed between the commonport of the radio frequency switch and an antenna port, and configuredto form a first coupling signal with the signal wiring, wherein aresonant frequency of the coupler related to the first coupling wiringis dependent on a capacitance of switch devices in a switch-off stateamong the switch devices, and a mutual capacitance and a mutualinductance between the signal wiring and the first coupling wiring. 2.The radio frequency switch circuit of claim 1, wherein the radiofrequency switch comprises first to N-th band switch circuits, whereineach of the first to N-th band switch circuits comprises a series switchcircuit comprising one or more switch devices connected between acorresponding signal port of first to N-th signal ports and the commonport, and a shunt switch circuit comprising one or more switch devicesconnected between a corresponding signal port of first to N-th signalports and a ground, and wherein the resonant frequency of the couplerrelated to the first coupling wiring is dependent on the inductance ofswitch devices in a switch-off state among the switch devices and themutual capacitance and the mutual inductance between the signal wiringand the first coupling wiring.
 3. The radio frequency switch circuit ofclaim 1, wherein the coupler further comprises a second coupling wiringspaced apart from the first coupling wiring and adjacent to the signalwiring and the antenna port to form a second coupling signal with thesignal wiring, and wherein a resonant frequency of the coupler relatedto the second coupling wiring is dependent on the mutual capacitance andthe mutual inductance between the signal wiring and the second couplingwiring and a capacitance of switch devices in a switch-off state amongthe switch devices.
 4. The radio frequency switch circuit of claim 3,wherein the first coupling wiring is a coupling wiring in a firstdirection for monitoring the signal transmission strength of abidirectional coupler, the second coupling wiring is a coupling wiringin a second direction for monitoring the signal reception strength ofthe bidirectional coupler, opposite to the first direction of thebidirectional coupler.
 5. The radio frequency switch circuit of claim 3,wherein the radio frequency switch comprises first to N-th band switchcircuits, wherein each of the first to N-th band switch circuitscomprises a series switch circuit comprising one or more switch devicesconnected between a corresponding signal port of first to N-th signalports and the common port, and a shunt switch circuit comprising one ormore switch devices connected between a corresponding signal port offirst to N-th signal ports and a ground, and wherein the resonantfrequency of the coupler related to the second coupling wiring isdependent on the mutual capacitance and the mutual inductance betweenthe signal wiring and the second coupling wiring and a capacitance ofswitch devices in a switch-off state among the switch devices.
 6. Theradio frequency switch circuit of claim 1, wherein the resonantfrequency of the coupler related to the first coupling wiring is thesame as a frequency of the first band signal transmitted from the radiofrequency switch to the coupler.
 7. The radio frequency switch circuitof claim 2, wherein the resonant frequency of the coupler related to thefirst coupling wiring is based on${{Fres} = {\frac{1}{2\;\pi*{Coff}}\left( {\sqrt{\frac{Cm}{Lm}} - \frac{1}{Zo}} \right)}},$where Coff is a capacitance of switch devices in a switch-off stateamong the switch devices, Cm is a mutual capacitance between the signalwiring and the first coupling wiring, Lm is a mutual inductance betweenthe signal wiring and the first coupling wiring, and Zo is an intrinsicimpedance of the corresponding signal port.
 8. The radio frequencyswitch circuit of claim 1, wherein the radio frequency switch and thecoupler are implemented as a single integrated circuit.
 9. A radiofrequency switch circuit, comprising a radio frequency switch comprisingswitch devices connected between a signal port and a common port; and acoupler comprising a signal wiring comprising one end connected to thecommon port and another end connected to an antenna port, and a firstcoupling wiring disposed coextensive to the signal wiring to form acoupling with the signal wiring and configured to produce a firstcoupling signal, wherein the radio frequency switch and the coupler areimplemented as a single integrated circuit.
 10. The apparatus of claim9, wherein the coupler is directly connected to the radio frequencyswitch without a matching circuit.
 11. The apparatus of claim 10,wherein the radio frequency switch comprises first to N-th band switchcircuits, wherein each of the first to N-th band switch circuitscomprises a series switch circuit comprising one or more switch devicesconnected between a corresponding signal port of first to N-th signalports and the common port, and a shunt switch circuit comprising one ormore switch devices connected between a corresponding signal port offirst to N-th signal ports and a ground, and wherein a resonantfrequency of the coupler related to the first coupling wiring isdependent on a mutual capacitance and a mutual inductance between thesignal wiring and the first coupling wiring, and a capacitance of switchdevices in a switch-off state among the switch devices.
 12. The radiofrequency switch circuit of claim 11, wherein the coupler furthercomprises a second coupling wiring spaced apart from the first couplingwiring and adjacent to the signal wiring and the antenna port to form asecond coupling signal with the signal wiring, and wherein a resonantfrequency of the coupler related to the second coupling wiring isdependent on the mutual capacitance and the mutual inductance betweenthe signal wiring and the second coupling wiring and a capacitance ofswitch devices in a switch-off state among the switch devices.
 13. Theradio frequency switch circuit of claim 11, wherein the first couplingwiring is a coupling wiring in a first direction for monitoring thesignal transmission strength of the bidirectional coupler, and thesecond coupling wiring is a coupling wiring in a second direction formonitoring the signal reception strength of the bidirectional coupler,opposite to the first direction of the bidirectional coupler.
 14. Theradio frequency switch circuit of claim 9, wherein the resonantfrequency of the coupler related to the first coupling wiring is thesame as a frequency of the first band signal transmitted from the radiofrequency switch to the coupler.
 15. The radio frequency switch circuitof claim 11, wherein the resonant frequency of the coupler related tothe first coupling wiring is based on${{Fres} = {\frac{1}{2\;\pi*{Coff}}\left( {\sqrt{\frac{Cm}{Lm}} - \frac{1}{Zo}} \right)}},$where Coff is a capacitance of switch devices in a switch-off stateamong the switch devices, Cm is a mutual capacitance between the signalwiring and the first coupling wiring, Lm is a mutual inductance betweenthe signal wiring and the first coupling wiring, and Zo is an intrinsicimpedance of the corresponding signal port.
 16. A radio frequency switchapparatus, comprising: a radio frequency switch comprising switchdevices connected between a signal port and a common port, andconfigured to switch a first band signal; a coupler comprising a firstcoupling wiring disposed adjacent to a signal wiring formed between theinterstage matching circuit and an antenna port to form a first couplingsignal with the signal wiring; and an interstage matching circuitconnected to the common port and configured to perform impedancematching between the radio frequency switch and the coupler, wherein aresonant frequency of the coupler related to the first coupling wiringis dependent on a capacitance of switch devices in a switch-off stateamong the switch devices, and a mutual capacitance and a mutualinductance between the signal wiring and the first coupling wiring. 17.The radio frequency switch apparatus of claim 16, wherein the radiofrequency switch comprises first to N-th band switch circuits, whereineach of the first to N-th band switch circuits comprises a series switchcircuit comprising one or more switch devices connected between acorresponding signal port of first to N-th signal ports and the commonport, and a shunt switch circuit comprising one or more switch devicesconnected between a corresponding signal port of first to N-th signalports and a ground, and wherein the resonant frequency of the couplerrelated to the first coupling wiring is dependent on a mutualcapacitance and a mutual inductance between the signal wiring and thefirst coupling wiring and a capacitance of switch devices in aswitch-off state among the switch devices.
 18. The radio frequencyswitch apparatus of claim 16, wherein the coupler further comprises asecond coupling wiring spaced apart from the first coupling wiring, andadjacent to the signal wiring and the antenna port to form a secondcoupling signal with the signal wiring, and wherein a resonant frequencyof the coupler related to the second coupling wiring is dependent on acapacitance of switch devices in a switch-off state among the switchdevices, and a mutual capacitance and a mutual inductance between thesignal wiring and the second coupling wiring.
 19. The radio frequencyswitch apparatus of claim 18, wherein the radio frequency switchcomprises first to N-th band switch circuits, wherein each of the firstto N-th band switch circuits comprises a series switch circuitcomprising one or more switch devices connected between a correspondingsignal port of first to N-th signal ports and the common port, and ashunt switch circuit comprising one or more switch devices connectedbetween a corresponding signal port of first to N-th signal ports and aground, and wherein the resonant frequency of the coupler related to thesecond coupling wiring is dependent on a capacitance of switch devicesin a switch-off state among the switch devices, and a mutual capacitanceand a mutual inductance between the signal wiring and the secondcoupling wiring.
 20. The radio frequency switch apparatus of claim 16,wherein the resonant frequency of the coupler related to the firstcoupling wiring is the same as a frequency of the first band signaltransmitted from the radio frequency switch to the coupler.
 21. Theradio frequency switch apparatus of claim 17, wherein the resonantfrequency of the coupler related to the first coupling wiring isdependent on${{Fres} = {\frac{1}{2\;\pi*{Coff}}\left( {\sqrt{\frac{Cm}{Lm}} - \frac{1}{Zo}} \right)}},$where Coff is a capacitance of switch devices in a switch-off stateamong the switch devices, Cm is the mutual capacitance between thesignal wiring and the first coupling wiring, Lm is the mutual inductancebetween the signal wiring and the first coupling wiring, and Zo is anintrinsic impedance of the corresponding signal port.
 22. The radiofrequency switch apparatus of claim 16, wherein the radio frequencyswitch and the coupler are implemented as a single integrated circuit.